Cartridge Alignment

Any master lacquer disc is cut with a mastering lathe in a tangent way. This means that the cutter head passes over the disc in a straight line, from the edge to the center.
Most turntables are fitted with radial-pivot tone arms – moving with a slight arc across the record surface. To achieve the best arc-to-radii ratio the arm/cartridge assembly needs to be adjusted at a specific distance between turntable platter spindle and tone arm horizontal pivot. This is called overhang.

Overhang adjustment can be set by either changing the tone arm’s distance from platter center or moving the cartridge to or fro in the tone arms’ head-shell. For instance: SME tone arms are adjusted at the mounting base and Triplanar arms have slots in the head-shell to move the cartridge inward or outward.

If you do not make an effort to adjust the cartridge alignment properly then it is all in vain. Out-of-alignment cartridges can make new records sound terrible and aligned cartridge can make poor records sound good – latter being depending on previous phono equipment.

It comes down to the fact that you want the stylus to move closest to the linear cutting line. Protractors help to spread out the slight tracking error to be as low as possible over the whole record. See diagram.
Because the radial-pivot causes the arm to move in an arc over the groove-area of the record it will, at the edge & center of the record, be above the cutter-line and, in the middle, under the cutter-line.

Good protractors can be found on websites like Vinyl Engine and The Analogue Department. Download one today and check your alignment. See my link list.

GD

NB - If you have a linear tracking tone arm the you dont have to worry much. It scans the record the way that the master was cut - in a tangent line.